Automatic output mode select for an actuator controller

Abstract

Methods and systems are disclosed for automatically controlling the mode of an output that can be coupled to one of several types of actuators or the like. In one illustrative embodiment, an actuator controller is provided that can automatically detect what controlled mode an output of the controller should be set, and set the controlled mode accordingly. In some cases, the actuator controller may monitor a measure related to the resistance of the load, and set the controlled mode of the output to a first controlled mode if the measure that is related to the resistance of the load is below a threshold value, and set the controlled mode of at least selected outputs to a second controlled mode if the measure that is related to the resistance of the load is above a threshold value. The controlled modes may, in some cases, correspond to a current controlled mode and a voltage controlled mode, but this is not required.

1. A controller adapted to drive a load, wherein the load has a resistance, comprising:
 an output that can drive the load in either a current controlled mode or a voltage controlled mode; 
 a determining block for determining a measure related to the resistance of the load, wherein the determining block includes a current sensing block and a voltage sensing block, the current sensing block is configured to sense a measure related to the current passing through the load, the voltage sensing block is configured to sense a measure related to a voltage across the load, wherein the measure related to the resistance of the load is determined by comparing the measure related to the current passing through the load and the measure related to the voltage across the load; and 
 wherein the controller enters one of the current controlled mode or the voltage controlled mode depending on the measure related to the resistance of the load determined by the determining block. 
 
     
     
       2. The controller of  claim 1  wherein the controller automatically enters either the current controlled mode or the voltage controlled mode according to the determined measure related to the resistance of the load. 
     
     
       3. The controller of  claim 1  wherein the current controlled mode is entered if the measure related to the load resistance is less than a threshold value. 
     
     
       4. The controller of  claim 3  wherein the voltage controlled mode is entered if the measure related to the load resistance is greater than the threshold value. 
     
     
       5. The controller of  claim 4  wherein the threshold value corresponds to a resistance value of about 500 ohms. 
     
     
       6. The controller of  claim 1  wherein the current sensing block includes a current controlled voltage source (CCVS) that has an op-amp and at least two voltage dividers. 
     
     
       7. The controller of  claim 6  wherein the voltage sensing block includes a voltage controlled voltage source (VCVS) that has at least one voltage divider. 
     
     
       8. The controller of  claim 7  wherein either the current controlled voltage source or the voltage controlled voltage source are configured to control a feedback path that is used to at least partially control a drive signal to the load. 
     
     
       9. A method for driving a load in either a voltage controlled mode or a current controlled mode, the method comprising:
 determining a measure related to the resistance of the load; 
 comparing the measure related to the resistance of the load to a threshold resistance; and 
 automatically driving the load in the current controlled mode if the measure related to the resistance of the load is below the threshold resistance; and 
 automatically driving the load in the voltage controlled mode if the measure related to the resistance of the load is above the threshold resistance. 
 
     
     
       10. The method of  claim 9  wherein the threshold resistance corresponds to a resistance value of about 500 ohms. 
     
     
       11. A method for driving an actuator in either a voltage controlled mode or a current controlled mode, the method comprising:
 determining a measure related to the current passing through the load; 
 determining a measure related to the voltage across the load; and 
 comparing the measure related to the current through the load to the measure related to the voltage across the load. 
 
     
     
       12. The method of  claim 11  further comprising:
 driving the actuator in the current controlled mode if the measure related to the current passing through the load is greater than the measure related to the voltage across the load; and 
 driving the actuator in the voltage controlled mode if the measure related to the voltage across the load is greater than the measure related to the current passing through the load. 
 
     
     
       13. The method of  claim 12  wherein the measure related to the current passing through the load is provided by a current controlled voltage source (CCVS) having a transresistance. 
     
     
       14. The method of  claim 13  wherein the measure related to the voltage across the load is provided by a voltage controlled voltage source (VCVS) having a gain. 
     
     
       15. The method of  claim 14  wherein the transresistance of the current controlled voltage source (CCVS) is adjustable. 
     
     
       16. The method of  claim 15  wherein the gain of the voltage controlled voltage source (VCVS) is adjustable. 
     
     
       17. A controller adapted to drive a load, wherein the load can be of a first type or a second type, the first type of load is expecting to be driven in a current controlled mode and the second type of load is expecting to be driven in a voltage controlled mode, the controller comprising:
 an output that can be used to drive the load in either a current controlled mode or a voltage controlled mode; 
 a control circuit for automatically determining whether the load is of the first type or the second type, and for automatically driving the output of the controller in the current controlled mode if the load is of the first type and for automatically driving the output of the controller in the voltage controlled mode if the load is of the second type, wherein the control circuit includes a current sensing block and a voltage sensing block, the current sensing block being configured to sense a measure related to the current passing through the load, and the voltage sensing block being configured to sense a measure related to a voltage across the load, wherein the load type is determined by comparing the measure related to the current passing through the load and the measure related to the voltage across the load. 
 
     
     
       18. The controller of  claim 17  wherein the control circuit has a feedback signal that is used to help control the drive delivered to the load, wherein the feedback signal is dependent on the current delivered to the load when the load is of the first type, and the feedback signal is dependent on the voltage across the load when the load is of the second type. 
     
     
       .  19 . The controller of  claim 17  wherein the load is the first type when the measure related to the current passing through the load is greater than the measure related to the voltage across the load, and wherein the load is the second type when the measure related to the voltage across the load is greater than the measure related to the current passing through the load.